SOLUTION: The sum of n terms of the series 4+14+30

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Question 899429: The sum of n terms of the series 4+14+30
Answer by richwmiller(17219) About Me  (Show Source):
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S = ½(2*A1 + (n-1)d)n
A1=4
d=16
S = ½(2*4 + (n-1)16)n
S = ½(8 + (n-1)16)n
S= (4 + (n-1)8)n
S=(4+8n-8)*n
S=(8n-4)*n
S=8n^2-4n